Ball-grinding machine.



CARL ALBERT HIRTH, OF CANNS'I'ATT-STUTTGART, GERMANY,

BALL-GRINDITVG MACHINE.

Specifieation of Letters Patent.

Application filed January 16, 1909. Serial 110,472,716.

To all whom it may concern:

Be it known that I, CARL ALBERT HIRTH,

,asubject of the Emperor'of Germany, citizen of Cannst-att-Stuttgart,Germany, residing at CannstattStuttgart, Germany, have inventednew anduseful Improvements in or Relating to Ball-Grinding Machines, of whichthe following is aspecification.

This invention relates, to ball grinding having annular grooves, thedisks operating together in pairs, one of them being stat on- :ary andhaving in one place an interruption of all the annular grooves in orderto enable the balls to leave their-particular groove and to enteranother, in which manner a greater degree of uniformity is imparted tothe balls in the same annular groove.

Owing to the fact that the pair of ball than would be if the ballsremained always grinding disks are ressed against each-other byspring-or weig t pressure, the one-sided interruption or opening in theone disk causes a one-sided pressure on the counter disk since the ballsare located between the two disks on that side of the center opposite tothe interruption or opening While on the interrupted side the balls passfrom between the disks through-said opening and consequently allow thedisks to spring or be pressed nearer together on the interru ted side.The balls are therefore submitte unequal pressure during grinding and itis therefore necessary to make the disks and shafts very strong, whichhowever, does not prevent unequal wear of the stationary disk takingplace and as a consequence more frequent adjustment of the parts isrendered necessary The object of the present invention 1s to complishedby providing, instead of a single interrupting ga in all the annulargrinding grooves, a plura ity of gaps distributed over the workingsurface. The plurality of gaps are so located around the workingsurfaces of one or-'each disk that an equalization of pressureis'maintained between the air of disks, and as a result, an approximatey complete uniformity in the effect of the pressure upon the balls isobtained. In other words, the interrupting gaps of the grinding groovesare symmetrically distributed over the working surfaces so that the lossof pressure caused by a gap in the one disk against the other disk isequalized by a corresponding reduction of pressure on the opposite sideof the center. The gaps are symmetrically disposed on opposite sides ofthe center so that when the balls'leave the grooves and pass 1nto a,gapon one side of the center, a corresponding gap on the opposite side ofthe center receives balls from the grooves so that the pressure onopposite sides of the center remains uniform. It, will be seen thereforethat the portions of the disk where the balls are being ground in thegrooves, and also Where they are removed-from the grooves, beingequalized or symmetrically disposed about the centerofthe disk auniformity of pressure is applied to the balls around thewhole surface-.of the disks.

I-n'order that the invention may be clearly understood reference will bemade in the following further description to the accompanying drawing,wherein Figure 1 shows in side elevation a pair of grinding disksmounted on their-spindle. Figs. 2, 3 and 4, are front elevations orfaceviews of one of the, disks and illustrate as examples" differentarrangements of the interrupting gaps in the disk according-to thisinvention. Figs. 5 and 6 show the front or facewiews of two disksadapted to act together, both being provided with gaps.

A ball grinding machine, of the preferred construction, comprises mainlya stationary disk at and a rotatory disk I) mounted upon the shafte therotatory disk b being pressed against the stationary disk a by means ofPatented Nov. 9, 1909.

avoid these disadvantages, and this is aoa'spring c. Thedisk a is madeof metal and is provided with concentric annular grooves f which serveto guide the balls cl being ground and rolling between the two disks.The disk I) may be made of metal or of a'suitable grinding material suchas emery. I i I The stationary disk 0; has hitherto been furnished withaninterrupting gapon one side of thecenter z. e. on one side of theshaft 6 on which the diskb rotates, said gap embracing all the annulargrooves f and allowing the balls -to leave the annular grooves at thecommencement of the gap in order to enter, at the end of said gap,different grooves. The present invention flhowever, provides severalgaps for the purpose of transferring the balls from one .mnu1ar grindinggroove f to another. It has been assumed in the Fig. 1 that thesegaps-are all provided in the stationary disk, the channels 9 taking theballs from the machineand the channels IL taking them back again. Thisinvention is not concerned with the means which may be employed to bothguide the balls vfrom one gap to another outside.-

the machine and-mix the balls between their being removed from and againintroduced into the machine. For these purposes any desirablemeans maybe employed and the present invention comprehends only the provision andparticular location of the plurality of gaps whereby the pressure uponthe balls between the two disks is uniform all over or around theworking surfaces.

In the examples illustrated in the accompanying drawing, for the sake ofclearness it is assumed that only six annular grooves f are provided,although generally there is a considerably greater number.

In the arrangement illustrated in Fig. 2, three disk gaps 1 2, 3 areprovided. The gaps l and 2 break the outermost and the two innermostannular grooves f, Whereas the symmetrically opposite gap 3 breaks thethree intermediate annular grooves. In this way the loss of pressure onopposite sides of the center owing to the balls leaving the grooves fand entering the gaps is equal, :hef' balls leaving a uniform number ofgrooves on opposite sides of the center.

In Fig. 3 the disk gap 1 breaks the two outer annular grooves f, the gapQ the two middle grooves, and the gap 3" the two inner grooves. The saidgaps-are dlsposed at 120 relatively to each other through the center sothat the pressure is approximately equally distributed over the disk.

In Fig. a each of the annular'grooves f is broken separately. The gapsland 2, placed on opposite sides of the center, break the w outsideannular grooves, the gaps 3-and season a break the two middle grooves,and the gaps 5 and 6 the two inner grooves. 111' this example, foneverytwo opposite gaps viz. l and 2, 3 and 4, 5 and 6 the loss of pressure isequalized with great approximation.

Although in the arrangements of the gaps illustrated in Figs. 2, 8 andat the equalization of the pressure is not perfect on account of theunequal distance of the gaps from the center of the disk, neverthelessa. perfectly equal pressure could be obtained by more accuratelydisposing the gaps, say at slightly different angles relatively to eachother or by making the gaps of different lengths.

In the example shown in Fig. -l-where each annular groove f is brokenseparately by the l to 6, the balls arriving at said gap in each groovecan be collected. separately and be mixed systematically in any desiredsequence in order to reintroduce them into different grooves as desired.By this means the uniformity of the balls grr'und in one charge isgreatly increased.

It is immaterial in the type of machine to which the present inventionis applied, whether the shaft 6 of the disks a and Z) is arra'ngedhorizontally, vertically or at'auy desired angle.

Although the gaps in the hereinbeiore described construction areillustrated and described as being provided in one disk only, viz. thestationary disk (1 yet such gaps may, if desirable be formed in both ofthe disks, as shown in Figs. 5 and (3 which illustrate the faces of twodisks adapted to work together. The stationary disk at is provided inthis case with three gaps which break the outermost, the third and iifthgrooves. The rotating disk Z) has also three gaps which break the secondgroove from the outside, and the fourth and sixth grooves. In both disksthe interrupting gaps are arranged symmetrically, thus compensating orequalizing the pressure.

What I claim then is 1. A. ball grinding machine having in com binationwith a pair of grinding disks, one of said disks having a series ofannular grooves and a plurality of gaps which interrupt said grooves totransmit the balls from one groove to another said gaps bein ar rangedsymmetrically around the center to equalize the pressure between thedisks, substantially as described.

2. A. ball grinding machine having in combination with a pair ofgrinding di is each furnished with a series'of annular grooves on theirmeeting faces, one of said disks having a plurality of gaps whichinterrupt said grooves to transmit the balls from one groove to anothersaid gaps being arranged sym metrically around the eentex to equalizethe 1 ranged symmetrically around the center to equalize the pressurebetween the disks, sub- 5 pressure between the disks, substantially asdeseribe..

3; A ball grinding machine having in 00111 bination with a pair ofgrinding disks each furnished with aseries of annular grooves on theirmeefiingfaces, each of said disks having a plurality of openingsWhichiiiter- I'upt said groovesio transmit the balls from 10 one grooveto another said gaps being 211"- st'antihlly as described. I i

- In test-imeny whereof I have signed my heme to this specificatien inthe presence of 15 two subscribing Witnesses.

CARL ALBERT HIRTHL Witnesses:

IWAN Rmsz, l PAUL WILHELM FUNCK.

